Such well-known underwater installations include a riser pipe that extends from the seabed as far as an intermediate area overlying the seabed and situated below the surface and a flexible pipe connected to extend the riser pipe and the flexible pipe extends catenary fashion from the intermediate area to the surface where it is connected to a surface installation. The riser pipe is kept substantially vertical by means of a float submerged in the intermediate area. This type of installation makes it possible to raise hydrocarbons from the seabed to the surface without being constrained by disturbances of the surface linked to swell, currents or winds.
The document WO2009/112 687 describes an underwater installation of this type. The underwater installation usually includes a frame enabling the end of the riser pipe and the float to be connected together, and the frame is equipped with a curved swan-neck pipe that extends the riser pipe. The pipe has a free end provided with a connecting end fitting. In a first installation phase, the frame and the float are installed to hold the riser pipe in vertical equilibrium. In a second installation phase the flexible pipe terminated by a connector is connected to the end fitting, from the surface, so as to establish the connection between the riser pipe and the flexible pipe. To this end, the connector is specifically equipped with a retractable flange and is installed at the end of the flexible pipe. It approaches the frame as the flexible pipe is paid out from the surface. As for the frame, it includes retaining members and the retractable flange is then engaged in the retaining members. More of the flexible pipe is paid out and the connector then tilts around the retaining means so that it abuts against a bearing member and faces the end fitting on the pipe. The connector is then driven toward the end fitting by retracting the flange to connect them together.
Difficulties arise in connecting the connector to the end fitting at greater depths of water. In fact, the riser pipes are longer and consequently heavier. The same gees-fer applies to the flexible pipes, and the forces to be exerted on the connector are consequently higher. Now the latter connectors are fragile and costly. Moreover, during the phase of moving the connector and the frame closer to each other, and because of the masses involved, the slightest impacts can have an impact on the integrity of the connector, notably when the connector tilts and comes into contact with the bearing member.
Also, a problem that arises and that the present invention aims to solve is to provide an underwater connection assembly that makes it possible to preserve the integrity of the connector during connection.